a b s t r a c t A new imidazole functionalized anthracene based Schiff base (L) was synthesized and it's selective col-orimetric as well as fluorescence responses to trivalent metal cations (Al 3+ , Fe 3+ and Cr 3+) over a variety of divalent and monovalent metal cations in 1:1 methanol–water mixed solvent and in live HeLa cells were demonstrated. These selective colorimetric and fluorescence responses were explained as a consequence of protonation of L, where the lower K sp values of M 3+ (Al 3+ , Fe 3+ and Cr 3+) facilitated the generation of H + through hydrolysis. This fluorogenic behavior of the ligand L was further confirmed by theoretical calculations.